1. Field of the Invention
This invention relates to a bolt forming header for forming rod-shaped blanks into bolts, and more particularly to a device for positioning the backward stroke end of a shearing blade for use in a bolt forming header.
2. Description of the Prior Art
Heretofore, the forward and the backward stroke ends of a shearing blade employed in conventional devices of the kind specified have been determined by means of a cam mechanism only. Stating in brief, according to the United Kingdom Pat. No. 1,026,261, there has been disclosed an arrangement in which a shearing slide member or piece having a shearing blade mounted on the leading end thereof can be driven by the cooperation of cam plates and a lever adapted to be driven by the cam plates so that the forward and the backward stroke end of the shearing blade can be determined by the design of the cam plates. Furhter, the Japanese Utility Model Registration Publication No. 17162/64 discloses an arrangement in which a shearing slide member or piece having a shearing blade mounted on the leading end thereof is connected through a slider member to a cam plate having a groove formed therein so that the forward and the backward stroke end of the shearing blade can be determined by the design of the cam groove.
In the above-mentioned prior art devices, the respective sheared faces of sheared blanks become rough, because a sufficient shearing speed and shearing force can not be applied to the shearing blade. As a result, it is impossible to machine the sheared blank as it is so as to make it into a finished product.